<?php
/**
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Cloud
 * @subpackage DocumentService
 * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */

require_once 'Zend/Cloud/DocumentService/QueryAdapter.php';

/**
 * Generic query object
 *
 * Aggregates operations in an array of clauses, where the first element
 * describes the clause type, and the next element describes the criteria.
 *
 * @category   Zend
 * @package    Zend_Cloud
 * @subpackage DocumentService
 * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Cloud_DocumentService_Query implements Zend_Cloud_DocumentService_QueryAdapter {
	/**
	 * Known query types
	 */
	const QUERY_SELECT = 'select';
	const QUERY_FROM = 'from';
	const QUERY_WHERE = 'where';
	const QUERY_WHEREID = 'whereid'; // request element by ID
	const QUERY_LIMIT = 'limit';
	const QUERY_ORDER = 'order';
	
	/**
	 * Clause list
	 *
	 * @var array
	 */
	protected $_clauses = array ();
	
	/**
	 * Generic clause
	 *
	 * You can use any clause by doing $query->foo('bar')
	 * but concrete adapters should be able to recognise it
	 *
	 * The call will be iterpreted as clause 'foo' with argument 'bar'
	 *
	 * @param  string $name Clause/method name
	 * @param  mixed $args
	 * @return Zend_Cloud_DocumentService_Query
	 */
	public function __call($name, $args) {
		$this->_clauses [] = array (strtolower ( $name ), $args );
		return $this;
	}
	
	/**
	 * SELECT clause (fields to be selected)
	 *
	 * @param  null|string|array $select
	 * @return Zend_Cloud_DocumentService_Query
	 */
	public function select($select) {
		if (empty ( $select )) {
			return $this;
		}
		if (! is_string ( $select ) && ! is_array ( $select )) {
			require_once 'Zend/Cloud/DocumentService/Exception.php';
			throw new Zend_Cloud_DocumentService_Exception ( "SELECT argument must be a string or an array of strings" );
		}
		$this->_clauses [] = array (self::QUERY_SELECT, $select );
		return $this;
	}
	
	/**
	 * FROM clause
	 *
	 * @param string $name Field names
	 * @return Zend_Cloud_DocumentService_Query
	 */
	public function from($name) {
		if (! is_string ( $name )) {
			require_once 'Zend/Cloud/DocumentService/Exception.php';
			throw new Zend_Cloud_DocumentService_Exception ( "FROM argument must be a string" );
		}
		$this->_clauses [] = array (self::QUERY_FROM, $name );
		return $this;
	}
	
	/**
	 * WHERE query
	 *
	 * @param string $cond Condition
	 * @param array $args Arguments to substitute instead of ?'s in condition
	 * @param string $op relation to other clauses - and/or
	 * @return Zend_Cloud_DocumentService_Query
	 */
	public function where($cond, $value = null, $op = 'and') {
		if (! is_string ( $cond )) {
			require_once 'Zend/Cloud/DocumentService/Exception.php';
			throw new Zend_Cloud_DocumentService_Exception ( "WHERE argument must be a string" );
		}
		$this->_clauses [] = array (self::QUERY_WHERE, array ($cond, $value, $op ) );
		return $this;
	}
	
	/**
	 * Select record or fields by ID
	 *
	 * @param  string|int $value Identifier to select by
	 * @return Zend_Cloud_DocumentService_Query
	 */
	public function whereId($value) {
		if (! is_scalar ( $value )) {
			require_once 'Zend/Cloud/DocumentService/Exception.php';
			throw new Zend_Cloud_DocumentService_Exception ( "WHEREID argument must be a scalar" );
		}
		$this->_clauses [] = array (self::QUERY_WHEREID, $value );
		return $this;
	}
	
	/**
	 * LIMIT clause (how many items to return)
	 *
	 * @param  int $limit
	 * @return Zend_Cloud_DocumentService_Query
	 */
	public function limit($limit) {
		if ($limit != ( int ) $limit) {
			require_once 'Zend/Cloud/DocumentService/Exception.php';
			throw new Zend_Cloud_DocumentService_Exception ( "LIMIT argument must be an integer" );
		}
		$this->_clauses [] = array (self::QUERY_LIMIT, $limit );
		return $this;
	}
	
	/**
	 * ORDER clause; field or fields to sort by, and direction to sort
	 *
	 * @param  string|int|array $sort
	 * @param  string $direction
	 * @return Zend_Cloud_DocumentService_Query
	 */
	public function order($sort, $direction = 'asc') {
		$this->_clauses [] = array (self::QUERY_ORDER, array ($sort, $direction ) );
		return $this;
	}
	
	/**
	 * "Assemble" the query
	 *
	 * Simply returns the clauses present.
	 *
	 * @return array
	 */
	public function assemble() {
		return $this->getClauses ();
	}
	
	/**
	 * Return query clauses as an array
	 *
	 * @return array Clauses in the query
	 */
	public function getClauses() {
		return $this->_clauses;
	}
}
